diff --git a/documentation/ref-manual/ref-images.xml b/documentation/ref-manual/ref-images.xml
index b12c49ac78..6b07dea19c 100644
--- a/documentation/ref-manual/ref-images.xml
+++ b/documentation/ref-manual/ref-images.xml
@@ -81,6 +81,11 @@
         <listitem><para><emphasis><filename>core-image-lsb</filename>:</emphasis>
             An image that conforms to the Linux Standard Base (LSB) specification.
             </para></listitem>
+        <listitem><para><emphasis><filename>core-image-testmaster</filename>:</emphasis>
+            An "known good" image referred to as a "master" image that you
+            can first boot into a separate partition and then interact with in
+            order to deploy the image to be tested.
+            </para></listitem>
         <listitem><para><emphasis><filename>core-image-lsb-dev</filename>:</emphasis>
             A <filename>core-image-lsb</filename> image that is suitable for development work
             using the host.